The chemical oxygen demand (COD) is a measure of the amount of oxygen consumed by the organic material within a water sample that is oxidized by a strong chemical oxidant, such as potassium dichromate (K2Cr2O7). Its main use is as an indicator of the organic and inorganic matter within water and effluent discharge giving a quantitative value of water quality. There are other tests that are also used to measure the organic content of a water body, such as the biological oxygen demand test. The biological oxygen demand (BOD) and can be found by collecting a sample from the watercourse and incubating it at 200C for five days, and calculating the oxygen used over the incubation period (Harrison 1996). The COD is often used when other methods are not as effective to be used. One advantage of the COD test over other tests, such as the BOD test is that it is relatively fast to carry out, for example the BOD test takes place over a five-day incubation period whilst the COD tests can be carried out in 2 hours; hence provides a much quicker indication of water quality.

Potassium dichromate, a bright orange salt used as...

Dale House - Darby Houses - Coalbrookdale

Heathfield School, Pinner

This property of the test has resulted in a wide range of usage when monitoring and controlling the organic content of industrial waste from effluent systems and the receiving water bodies.

Dichromate is often used as the oxidizing agent when determining the COD due to its ability to oxidise most materials and ease of manipulation (Chapman 1996). Test allows the organic matter within a sample to reduce the dichromate; any remaining dichromate is titrated with ferrous ammonium sulphate, FeSO4.(NH4)2SO4, where the Fe2+ ions are oxidised to Fe3+ by the remaining dichromate ions, Cr2O72-. The dichromate (Cr2O72-) is dissolved into a salt by the addition of sulphuric acid...

Citation styles:

Determination of the Chemical Oxygen Demand (COD) of River Water Samples. (2004, May 07). In WriteWork.com. Retrieved 03:36, August 18, 2017, from http://www.writework.com/essay/determination-chemical-oxygen-demand-cod-river-water-samples

More Science Essays essays:

... and about -180° C (about -290° F) on the dark side. It's atmosphere consists of sodium, helium, hydrogen, and oxygen. Mariner 10 also detected a magnetic field 1 percent that of the earth. Unlike that of the earth's moon ...

... antimatter to form, and they instantly destroy each other, producing fire and a thin haze of matter-apparently because slightly more matter than antimatter was formed.5 The fireball, and the smoke of its burning, was the universe at an age of ...

... the same time, the rotating right solid rocket booster impacted the intertank structure and the lower part of the liquid oxygen tank. These structures failed at 73.137 seconds as evidenced by the white vapors appearing in the intertank region. Within ...

The Future of NASA One hundred years from now, NASA's space program will not be so far advanced that people will be able to beam around the Universe or travel through time. However, unless something goes terribly wrong with the world, it is expected to advance tremendously. New, high-tech designs ...

... and not overpowering people with his radical theory Darwin was able to gain a large number of supporters in the biological community who in turn spread his theory more and more. It was through Darwin's connections that the vast majority ...

7 pages118Mar/19963.5

Students & Profs. say about us:

"Good news: you can turn to other's writing help. WriteWork has over 100,000 sample papers"